Method for a connection through a core network

ABSTRACT

In a method for the establishment of a connection between a first node (RNC 1 ) and a second node (RNC 2 ), both are connectable to a core network which comprises interconnected core network nodes (CN 1,  CN 2 ). The first node (RNC 1 ) signals a call request to a first core network node (CN 1 ). If the first node is an access node, it sends an initialization according to a framing protocol, wherein a set of parameters for the framing of information sent over the interface between the first access node (RNC 1 ) and the first core network node (CN 1 ). If the first node is no access node, a first control server (MSC 1 ) defines said set of parameters. The set of parameters is transmitted to the first core network node (CN 1 ) and the first core network node (CN 1 ) stores the parameter set. The first core network node (CN 1 ) initializes the connection (Co) to a further core network node according to said protocol and the further core network node stores the parameter set. The initialization of the connection (Co) to and the storing of parameters in further core network nodes is performed stepwise until a final core network node (CN 2 ) is reached which is connectable to the second access node (RNC 2 ). The final core network node (CN 2 ) initializes the connection (Co) to the second access node (RNC 2 ) according to said protocol and the second access node (RNC 2 ) stores the parameter set. A core network node and a program unit embodying the invention are also described.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a method according to thepreamble of claim 1. Devices and software programs embodying theinvention are also described.

BACKGROUND

[0002] Communication networks can be subdivided into core networks andaccess networks, the latter providing access to user equipment, forexample a wireless access for mobile user equipment to a radio accessnetwork. Core networks interconnect access networks and optionallyfurther networks, e.g. the Internet. In the UMTS architecture, an accessnetwork can be controlled by an RNC (radio network controller) which isconnected to the core network and provides access to the core network,i.e. serves as access node. In 3GPP (3 ^(rd) Generation PartnershipProject) Technical Specification 3G TS 25.415 V3.2.0, the interfacebetween the access node and a node in the core network is denoted as Iuinterface. Over the Iu interface, connections can be establishedaccording to the Iu user plane protocol.

[0003] RFCIs (radio access bearer subflow combination indicators) areindicators to sets of parameters which are generated by an RNC in radioaccess bearer (RAB) assignments. They indicate which service data unitformats are valid, for example for use in speech frames or in ratecontrol requests received from the core network, and how they areformatted. RFCIs determine the codec mode, especially allowed rates.When a transcoder is inserted into a connection, it receives dataframes, e.g. Iu frames, and relates the assigned RFCI to a codec mode inorder to decode the frames. In the same way, it must indicate the RFCIwhen it sends an encoded frame.

[0004] The Iu interface as specified in 3GPP Technical Specification 3GTS 25.415 terminates in a core network node, for example in an MSC or ina media gateway controlled by an MSC server, according to thearchitecture of the core network. In a core network node, the content ofdata sent over a connection can be changed. Especially, the payload orspeech coding can be adapted, for example due to the intervention ofsupplementary services like DTMF (Dual Tone Multifrequency) toneinsertion, supplementary services tone insertion, messages or conferenceconnections of user equipment.

[0005] For connections between nodes within the core network, differentprotocols are possible. Beside the Iu user plane protocol, I.366.2 is aprotocol defined by the ITU (International Telecommunication Union) asservice specific convergence sublayer (SSCS) used on AAL2 (AsynchronousTransfer Mode Adaptation Layer Type 2) for carrying service specificpayloads. Especially, it is the framing protocol proposed to be used forcarrying compressed voice. This requires the core network node toterminate the Iu interface and to establish an AAL2 connection with therequired SSCS for the selected speech coding type. A further framingprotocol is RTP (Real Time Protocol) which can be carried on an IPtransport layer in the core network for transmission of compressed voiceof a specified encoding.

[0006] A problem with both RTP and I.366.2 is that they are applicationdependent and transport layer dependant. If the coding type changesduring a connection, a new AAL2 connection or modification must be madewith the new SSCS profile. For an IP network, a new RTP profile must beused. This requires unnecessary overhead to carry the profiles with thepayload. A further problem with SSCS or RTP is that both are servicespecific. The protocols require modifications in standardization andimplementation for every new service.

[0007] In contrast to this, the Iu user plane protocol is definedservice independent. An Iu interface can be connected between two accessnodes, e.g. by using BICC (Bearer Independent Call Control) messages topass the bearer address used in a first access node from a server, e.g.an MSC, controlling it to the server controlling the other access node.In this case, it is disadvantageous that there is no control of the userplane. For example, when a handover is necessary or a supplementaryservice invocation occurs, the Iu connection has to be cancelled and anew Iu connection must be established which is very inefficient andwould degrade the service level. However, for most of the time in aconnection, supplementary services or other functions within theconnection path are not necessary and hence a virtually direct andtransparent connection between access nodes or an access node and atranscoder is advantageous.

[0008] The other described framing protocols do not carry the Iu userplane parameters. Transcoders are necessary to terminate the Iuconnection and need to receive the parameters sent by the Iu user planeinitialization procedure (RFCIs). If another of the above-describedframing protocols is used in the core network, the Iu user planeprotocol is terminated at the first core network node in the connection,e.g. a media gateway. The payload content is then mapped to the otherframing protocol. Furthermore, the RFCI initialization must be carriedby the other framing protocol and possibly mapped to the actual mode asthe framing is codec type specific. At the final core network node inthe connection; a transcoder to terminate the Iu connection to theaccess node must then be initialized and the payload content must bemapped back to the Iu user plane protocol which requires sufficientprocessing capacity.

[0009] It is also conceivable that parameter sets like RFCIs aretransferred from access nodes by out-band procedures, i.e. the corenetwork nodes are provided with parameter sets by a vertical controlprotocol from servers controlling them. This architecture is customaryin a telecommunication system with separate user plane comprising thecore network nodes and a control plane with the servers. Between theservers, the parameter sets can be transferred via the horizontal bearerindependent call control (BICC) protocol. The parameter sets can then betransferred to the core network nodes and stored during connectionset-up or are only sent when needed to modify a connection. Althoughthis solution allows establishing an Iu user plane connectiontransparently through the core network nodes, it has the disadvantagethat it requires a high amount of signaling traffic.

[0010] In the case, that inband signalling is used, two further problemscan occur. Firstly, that parameter sets sent by a first RNC and a secondRNC might by crossing. This happens for example, when a second RNC sendsa parameter set before it receives a parameter set from the first RNC.

[0011] Secondly, an RNC might start initializations without beingrequested by an MSC, a so-called unsolicited initiation. To recognisesaid initializations, core network nodes have to monitor the user planethey transport. As this consumes processor capacity in said core networknodes, this is not always favored.

SUMMARY AND DESCRIPTION OF THE INVENTION

[0012] It is the object of the present invention to obviate the abovedisadvantages and provide a simple method for the establishment of anefficient connection through a network, wherein the connection caneasily be controlled.

[0013] According to the invention, the method described in claim 1 or 11is performed. Furthermore, the invention is embodied in a node asdescribed in claim 21 or 22 and a program unit as described in claim 25.Advantageous embodiments are described in the dependent claims.

[0014] The proposed method establishes a connection between a firstaccess node and a second access node which are connectable over a corenetwork. An access node can also be a node connecting a furthercommunication network to the core network or a core network nodeterminating the connection in a transcoder. The core network comprisesinterconnected core network nodes, for example media gateways orcustomary mobile services switching centers (MSC). The first access nodeinitializes the connection to a first core network node according to aframing protocol. If the access node belongs to a different network, theinitialisation can be performed via a core network control node. Duringthe initialization, a set of parameters for the framing of informationsent over the interface between the first access node and the first corenetwork node is transmitted to the first core network node. The firstcore network node stores the parameter set in a memory.

[0015] In the embodiment according to claim 1, the first core networknode either decides or receives a decision from a core network controlnode or an access node whether an indicator is to be set, thattransparent Iu UP transmission is permitted. An indicator is set to“transparent transmission of Iu UP is permitted”. This has the effect,that the access nodes are not permitted to perform an unsolicitedinitialisation and that respectively the core network control nodes orcore network nodes can decide to remove the monitoring of Iu UP forinitialisation messages. The parameter indicating the setting of theindicator is sent to the access nodes during RAB assignment. The firstcore network node stores the indicator in its memory.

[0016] In the case that the indicator is set, the Iu UP handling in thecore network nodes can be switched in or switched out for example bycore network control nodes. It is then also required that no unsolicitedIu initialisation is received by the core network nodes. This isacceptable because the core network control node controls the RABAssignment and the edge core network nodes, for example the first andthe final control node. It is the edge core network nodes that needtheir Iu UP function switched in prior to a RAB assignment modification.

[0017] The control of this procedure can be initiated by the corenetwork control nodes at either end of the call, independently. A newprocedure in the RAB Assignment from the core network control node tothe RNC indicates that the RNC should maintain the Iu UP initialisationuntil instructed to change by a further RAB Assignment or RelocationRequest. The RNC can send the indicator, for example as a new field inthe IU UP initialisation PDU. This enables other core network nodes inthe call path to remove their Iu UP termination and monitoringfunctions.

[0018] Both in the embodiment according to claim 1 and 11, the firstcore network node then initializes the connection to a further corenetwork node according to said protocol and the further core networknode also stores the parameter set and, if applicable, the indicator. Inthis way, a stepwise initialization of the connection to further corenetwork nodes and storing of parameters and, if applicable, theindicator in the further core network nodes is performed until a finalcore network node is reached which is connectable to the second accessnode. It is possible that the second core network node is already thefinal core network node. The final core network node initializes theconnection to the second access node according to said framing protocoland the second access node stores the parameter set and, if applicable,the indicator.

[0019] The proposed method is simple and requires a low processingeffort in the nodes because no mapping between different framingprotocols is necessary. In a simple implementation, the core networknodes transfer the frames without evaluation of the content. However,every core network node can terminate the framing protocol, establishfurther connections or connections with different parameters and accessthe data in the frames using the stored parameters. Especially, theconnection can be controlled or adapted in every node with low delay andindependent of other nodes in the connection. Because only one protocolis used in a connection, there are no problems of adaptation and a fastevolution of services is possible. A virtual transparent connectionbetween access nodes and a transcoder, respectively between access nodesis possible. Preferably, the described method is performed in acommunication network.

[0020] The proposed method allows, however, also to change the framingprotocol between two nodes in the core network (e.g. between CN1 and CN2by use of RTP or 1.366.2) wherever required and where these otherframing protocols are defined for the service in question, because theframing protocol is initialized and can be terminated in each of thenodes. This requires more processing within these network nodes and isnot as flexible as the preferred method, but it allows the interventionof supplementary services within each node, as described below.

[0021] In a preferred embodiment, the core network nodes acknowledge theinitialization to the preceding node, i.e. a core network node or anaccess node. In this way, the initialization is terminated for thepreceding node. The acknowledgement is preferably sent before or duringthe initialization of the connection to a further core network node.

[0022] A preferable framing protocol is the Iu protocol which can beused inside a core network according to 3GPP specifications to carrypayload between core network nodes and to an edge of the network where,for example, the connection is terminated in a transcoder or in aterminating access node, e.g. an RNC. The Iu user plane protocol isinitialized in every node in the connection that may add a service tothe payload.

[0023] An advantageous core network node in the connection can insert afunction unit into the connection, e.g. break the transcoder freeoperation of the connection by inserting a transcoder or by inserting afunction unit providing a supplementary service. An insertion ofsupplementary services can occur inside media gateways without aninfluence on other nodes and links in the connection and is in this wayfast and simple to handle.

[0024] A preferable core network node can break the connection andinitialize a connection segment to a different core network node oraccess node according to said protocol, preferably using the sameparameter set for the connection segment as for the former connection.In this way, for example a handover of a connection between differentaccess nodes can be performed if the connection is terminated by amobile user equipment moving in a communication system or the connectioncan be redirected.

[0025] The second access node can initialize a reverse connection to thefinal core network node according to the protocol. A second set ofparameters for the framing of information is transmitted, and theinitialization is performed stepwise to the first access node, i.e. inthe same way as the first connection. It is preferable that both sets ofparameters are identical or at least enable a connection according to acommon subset of parameters.

[0026] It is possible that both access nodes receive a request fromcontrol nodes of the core network to establish a connection to therespective other access node. Especially in this case, both sets ofparameters can be incompatible, i.e. no common connection parameters canbe obtained from the sets although both sets may allow several differentconnection options. In this case, the processing system of a preferablecore network node checks both sets of parameters and inserts atranscoder into the connection which adapts the formats of the framessent according to the different parameter sets.

[0027] Alternatively, if a core network node detects that both sets ofparameters are incompatible, it sends a message to a control server forinitiating a modification of connection parameters by at least oneaccess node. The modification can be initiated by control messages sentto the respective access node.

[0028] The connection between two core network nodes can be establishedvia one or several switches, i.e. nodes in the core network which do notstore connection parameters and can not change connection parameters.

[0029] If a core network node is adapted to establish connectionsaccording to different framing protocols, it preferably checks theframing protocol defined in a request to initialize a connection andselects said framing protocol for the initialization of the connectionto a further node. In this way, a mapping between different protocols isavoided while several protocols can be used.

[0030] A core network node according to the invention, e.g. an MSC or amedia gateway, is interconnected with further core network nodes. It hasan interface for receiving an initialization request from an access nodeor a further core network node to establish a connection according to aframing protocol. A processing system is adapted to extract a set ofparameters for the framing protocol from the request and initialize theconnection to a further core network node or an access node according tosaid protocol. Optionally, the processing system determines an indicatorfor the permission of transparent Iu UP transmission after connectionestablishment. The determination can be performed by extracting theindicator from the initialisation request, by receiving it from a corenetwork control node, or by decision. The extracted parameter set and,if applicable, the indicator are stored in a memory. The indicator isevaluated for the monitoring of the payload. The core network node canpreferably perform any steps of the above described methods relating tothe core network node.

[0031] In the invention, a transparent transmission through core networknodes is preferably selected. In a non-transparent mode, a core networknode transmitting the user plane monitors the user plane forinitialisation messages.

[0032] In the transparent mode, unsolicited Iu UP (lu user plane)initialization, that is an Iu UP initialization starting withoutinvolving an MSC or MSC server, from an RNC during an active call is notpermitted. The RAB (radio access bearer) assignment contains a newparameter which indicates if the RNC is allowed to perform unsolicitedIu UP initializations or not. If the MSC Server has successfullynegotiated a TrFO (transcoder free operation) call it can then decide ifit wants the TrFO connection to be transparent or not. If the option isto support transparent Iu UP connections then it sets this parameter inthe RAB Assignment. The RNC then sets the new indicator in the Iu UPinitialization indicating this. This means that the RNC does notre-configure its set of parameter e.g. RFC's and TFC's mid-call withoutreceiving a new RAB Assignment or Relocation Request from the MSC.

[0033] In the case where an SRNC (serving RNC) receives an Iu frameindicating that an initialization procedure is active at the other endof the Iu UP, the RNC changes its RFCI set to match the set indicated bythe peer. That is, both RFCI sets, i.e. the set for uplink and the setfor downlink, match and are derived by the peer.

[0034] If the transparent mode is not supported by a core network node,the user plane has to be monitored for Iu UP initialization and mappingof RFCI allocation from the RNC interacting with said core network node,to any initializations received from a far end RNC is to be performed.

[0035] A program unit according to the invention can be stored on a datacarrier or be directly loadable into a core network node. The programunit comprises code for performing the steps of receiving a request toinitialize a connection according to a framing protocol, extracting aset of parameters for the framing of information according to saidprotocol, storing the parameter set. Optional is a step of deciding orreceiving a decision whether an indicator for the permission oftransparent transmission of Iu UP is permitted. Furthermore, the unitperforms the step of initializing the connection to a further corenetwork node or an access node according to said protocol, and, ifapplicable, forwarding the indicator. It can preferably perform anysteps of the above methods relating to the core network node.

[0036] The foregoing and other objects, features and advantages of thepresent invention will become more apparent in the following detaileddescription of preferred embodiments as illustrated in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]FIG. 1 shows a basic connection establishment according to theinvention.

[0038]FIG. 2 shows a connection establishment between two access nodes.

[0039]FIG. 3 shows a redirection of a connection between two accessnodes.

[0040]FIG. 4 shows a connection with an inserted pair of transcoders.

[0041]FIG. 5 shows the processing of a connection which is initiatedwith incompatible parameter sets by the access nodes.

[0042]FIG. 6 shows a basic connection establishment according to theinvention.

[0043]FIG. 7a shows a core network node transferring Iu UP in anon-transparent way.

[0044]FIG. 7b shows a core network node transferring Iu UP in atransparent way.

DETAILED DESCRIPTION OF. PREFERRED EMBODIMENTS OF THE INVENTION

[0045] In FIG. 1 the first steps of the initialization of a connectionaccording to the invention is depicted. The connection is establishedaccording to the Iu user plane protocol, which is terminated in everycore network node CN that may require modifying the user connection, forexample for a supplementary service intervention. From a first accessnode RNCI a message In1 to initialize a connection is sent to a firstcore network node CN1. In the example, the message In1 is an Iuinitialize packet data unit. A processing system of the first corenetwork node CN1 extracts a set of parameters, especially RFCIs, fromthe message In1 and stores them in a memory MEM1. The first core networknode CN1 sends an acknowledgement Ack1 of the message In1 to the firstaccess node RNCI and creates a further message In2 comprising theparameter set. The core network node CN1 can decide to allow transparentIu UP transmission after call establishment. In this case, an indicatorindicating the transparent transmission of lu UP is added to theparameter set or sent together with it. This can be implemented by amodification of the 3GPP TS 25.415 standard, allowing the addition ofsaid indicator. Message In2 is sent to a further core network node CN2which also extracts the parameter set and said indicator, stores it in amemory MEM2 and sends an acknowledgement Ack2 back to the first corenetwork node. By repeating the initialization stepwise for all nodes inthe connection, every node has control of the Iu user plane and servicedata unit formats passed in the initialization packet data unit.

[0046] Parameter sets, especially RFCIs, are generated according tocustomary specifications for communication networks by the access nodesRNC1, RNC2 as soon as a request to set up a connection is received. Fora transcoder free operation of a connection, there are generally twosets or RFCIs, being initialized from each access node to the other.Alternatively, the messaging from and between servers controlling thecore network nodes CN can be adapted to allow only one initialization,e.g. from the first access node RNC1. As shown in FIG. 2, the secondaccess node RNC2 waits in this case for the initialization from thefirst access node RNC1 sent stepwise via messages In1, In2, In3acknowledged by corresponding acknowledgements Ack1, Ack2, Ack3. In thesame way, the connection is then initialized backwards with the same setof parameters via messages In4, In5, In6 acknowledged by correspondingacknowledgements Ack4, Ack5, Ack6. In this way, incompatible parametersets can be avoided.

[0047] In a preferred embodiment of the invention, no initialization inbackward direction is performed if the indicator for a transparent Iu UPtransmission is set. As the same parameter set is used in eitherdirection, an initialization in backward direction is redundant. Toenable the usage of the same parameter set in uplink and downlinkbetween the final core network node CN2 and the second access node RNC2,the second access network node has to adapt both parameter sets, foruplink and downlink connection at initialization.

[0048]FIG. 3 shows an example of a redirection of an establishedconnection Co due to a relocation of the serving access node terminatingone end of the connection Co as indicated by arrow Ar. A relocation canfor example be necessary when a user moves in the coverage area of amobile communications network and a handover is performed between radiobase stations controlled by different controllers serving also as accessnodes RNC2, RNC3. A new radio access bearer is established by accessnode RNC3 to the core network node CN2, e.g. a media gateway, byperforming a new Iu user plane initialization with a message In which isacknowledged by acknowledgement Ack the core network node CN2. Theparameters initialized by the first access node RNC1 for the originalconnection are read from a memory in core network node CN2 andtransmitted in initialization message In′ with correspondingacknowledgement Ack′ to the new access node RNC3. The new access nodeRNC3 can use the set of parameters for both uplink and downlinkconnection to the network. The other nodes taking part in the connectionare left unaffected. In this way, a new connection segment Co′ can beestablished in a fast and simple way.

[0049] In an embodiment, the core network node CN2 transfers theparameters from message In by stepwise initialization back to the otheraccess node RNCI as depicted by initialization messages In″, In′″ withcorresponding acknowledgements Ack″, Ack′″. Preferably, message In″ isonly sent if the core network node CN2 detects that the parameter set inmessage In is compatible to those of the original connection Co. Elseprocedures as described with respect to FIGS. 4 and 5 can be initiated.

[0050] In FIG. 4, a connection Co between two access nodes RNC1, RNC2over core network nodes CN1, CN2 is shown with a pair of transcoders TRinserted into the connection. The insertion can be performed at any corenetwork node. The insertion can be performed for example into an ongoingconnection to provide a supplementary service or already during theestablishment of connection, Co if required by incompatible parametersets sent by the access nodes RNC1, RNC2. Preferably, the insertion of atranscoder TR is handled within a core network node CN1. Because thenecessary parameters for terminating the Iu user plane protocol arestored in the core network node CN1, they can be provided to thetranscoder TR fast and efficiently. Therefore, transcoder TR can beswitched into connection Co with minimum delay in a primed state.Consequently, speech and data frames can be received and transmittedcoherently during the insertion improving the in this period connectionquality.

[0051] In FIG. 5, the treatment of a mismatch of parameter sets in acommunication system with separate user plane UP and control plane CP isdescribed. The user plane UP comprises the core network nodes CN1, CN2and the access nodes RNC1, RNC2 while several servers MSC1, MSC2 forcontrolling these nodes CN, RNC are included in the control plane CP.Messages within the control plane CP can for example be transferredaccording to the BICC protocol, while the Iu user plane protocol issuitable for messages within the user plane UP.

[0052] In the example both access nodes RNC1, RNC2 have received fromthe respective servers MSC1, MSC2 a message to initiate a connectionwith a specific codec type. Accordingly, access node RNC1 begins toinitialize a connection with a message Inb while access node RNC2 beginsto initialize a connection with messages Ina, Ina′. The correspondingacknowledgements are not shown to simplify the figure. It is possible,that the access nodes RNC1, RNC2 select different active codec sets forthe initialization messages Ina, Inb which are incompatible.

[0053] Preferably, every core network node or specified core networknodes in the connection, e.g. media gateways connected to access nodes,compare the parameter sets received in the different initializationmessages Ina′, Inb. If a core network node CN1 determines that there isno match of supported modes—i.e. both access nodes RNC initializeseparate modes without a common mode the core network node CN1 in oneembodiment of the invention automatically inserts transcoders to allowthe successful establishment of the connection. In this case, thetranscoders in the core network node CN1 terminate two connections tothe respective access nodes RNC1, RNC2. The initialization of thereverse connections is then started from core network node CN1 with aninitialization messages containing the parameter set of message Inbtowards access node RNC1 and with an initialization messages containingthe parameter set of message Ina′ towards access node RNC2.

[0054] The alternative embodiment depicted in FIG. 5 allows to establisha transparent connection without transcoders if a common mode ispossible for both access nodes RNC. In this case, core network node CN1sends a message 51 to the controlling server MSC1, that the RFCI setsreceived in both messages Inb, Ina′ are incompatible. Message 51 can forexample be sent over an H.248 interface. Due to stored or requestedcapability information about the access nodes, the server MSC1 can thendecide whether it is necessary to modify the connection by sending backa message to the core network node CN1 to insert transcoders.

[0055] If, however, both access nodes RNC1, RNC2 are adapted toestablish a connection with a common mode, messages 53 for determining acorresponding mode can be sent to the servers controlling the accessnodes RNC1, RNC2. The servers MSC1, MSC2 can then send messages 52, 54to the respective access nodes RNC1, RNC2 to activate said mode andrepeat the initialization with new messages Ina, Inb. Messages 52, 54can for example be RANAP (Radio Access Network Application Protocol)messages.

[0056] If different framing protocols are supported in the core networkit is proposed that they are also negotiated in the control plane CPalong with the codec types and bearer connection characteristics. Inthis case, one framing protocol, e.g. Iu user plane, can be requested asthe preferred framing type, especially from a 3G access node. Thisprovides the opportunity to use Iu user plane framing end to end if aconnection transits a network supporting different framing protocols andthen again terminates in a 3G network. Compressed speech can then beconveyed through the core network without mapping between differentframing protocols. Further, any services can be supported in every corenetwork node after it has terminated the Iu user plane protocol. It canthen insert a transcoder without requiring a new User Planeinitialization or radio access bearer reestablishment.

[0057] Finally, if multiple framing protocols are used in a connection,the stepwise initialization of the RFCIs can also be adopted for theseprotocols.

[0058] In FIG. 6 a connection is set up between an access node from afurther network and a network controlled according to the invention. Acall request 61 is received in a core network control node GMSC. Thecore network control node GMSC decides to set an indicator that thetransparent Iu UP transmission is permitted. It defines a set ofparameter and sends the set of parameter, or an identification of saidset as well as the indicator to a first core network node CN1 in amessage 62.

[0059] In a further embodiment of the invention, the set of parametersand an acknowledgement are exchanged in a message sequence InAck betweenthe access node RNC1 and the first core network node CN1. In this case,only the decision to set the indicator is sent by the core networkcontrol node GMSC to the core network node.

[0060] In another embodiment of the invention, also the decision to setan indicator is taken by an access node, or the parameter indicatingsaid decision is sent by the core network control node GMSC to an accessnode. In those cases message 62 is not sent.

[0061] Independent from the source of the set of parameters orindicator, after the reception of said parameter set and the indicator,the first core network node CN1 continues the connection establishmentas described in FIG. 1. The initialization message and the accordingacknowledgement are depicted as the message sequences InAck′ and InAck″.

[0062] The difference between the non-transparent and the transparenttransmission of Iu UP is described in FIGS. 7a and 7 b using an Iu UPprotocol as an example.

[0063]FIG. 7a shows two core network nodes, monitoring the Iu UP herereferred to as lu SDUs-payload for initialization messages referred asIU PDU Type 14 while transferring it. In both nodes, the currently validRFCIs are stored.

[0064]FIG. 7b shows the same core network nodes transferring Iu UPtransparently.

[0065] The payload is not monitored, RFCIs are stored. In that case, thestored RFCI values will be used for the new connection segment. As thecore network nodes do not monitor the Iu UP for initialization messages,no unsolicited initialization must be sent to them.

[0066] The above embodiments admirably achieve the objects of theinvention. However, it will be appreciated that departures can be madeby those skilled in the art without departing from the scope of theinvention which is limited only by the claims.

1. Method for the establishment of a connection between a first node(RNC1) and a second node (RNC2) which are connectable to a core network,wherein the core network comprises interconnected core network nodes(CN1, CN2), characterized in that the first core network node (CN 1)receives a set of parameters for the framing of information sent overthe interface between the first access node (RNC1) and a first corenetwork node (CN1) for a connection (Co), the first core network node(CN1) stores the parameter set, a decision is taken to set an indicatorthat transparent transmission is performed after call establishment, thefirst core network node (CN1) initializes the connection (Co) to afurther core network node according to said protocol, including saidindicator, the further core network node stores the parameter setincluding said indicator, stepwise initialization of the connection (Co)to and storing of parameters and the indicator in further core networknodes until a final core network node (CN2) is reached which isconnectable to the second node (RNC2), the final core network node (CN2)initializes the connection (Co) to the second node (RNC2) according tosaid protocol and the second access node (RNC2) stores the parameter setincluding said indicator.
 2. Method according to claim 1, wherein thedecision to set an indicator is taken by a core network control node(MSC1) controlling the first core network node (CN1).
 3. Methodaccording to claim 1, wherein the decision to set an indicator is takenby the first core network node (CN1).
 4. Method according to claim 1,wherein the decision to set an indicator is taken by an access node(RNC1, RNC2).
 5. Method according to any preceding claim, wherein adecision to monitor payload for initialisation messages is taken by acore network control node and signalled to a core network node. 6.Method according to any preceding claim, wherein a core network controlnode decides to set a parameter that unsolicited Iu initialisations arenot permitted and sends said parameter to an access node.
 7. Methodaccording to any preceding claim, wherein a core network node (CN1, CN2)in the connection (Co) breaks the connection (Co) and initializes aconnection segment (Co′) to a different core network node or access node(RNC3) according to said protocol, using the same parameter set for theconnection segment (Co′) as for the connection (Co).
 8. Method accordingto any preceding claim, wherein the second access node (RNC2)initializes a reverse connection (Co) to the final core network node(CN2) according to the protocol, wherein a second set of parameters forthe framing of information is transmitted.
 9. Method according to claim8, wherein both sets of parameters differ and a core network node (CN1,CN2) inserts a pair of transcoders (TR) into the connection (Co). 10.Method according to claim 8, wherein both sets of parameters differ andthe final core network node (CN2) sends a message to a control server(MSC2) for initiating a modification of connection (Co) parameters bythe final access node (RNC2), the final access node (RNC2) changing boththe parameter sets for uplink and for downlink transmissions to thefinal core network node (CN2).
 11. Method for the establishment of aconnection between a first access node (RNC1) and a second access node(RNC2) which are connectable to a core network, wherein the core networkcomprises interconnected core network nodes (CN1, CN2), characterized inthat the first access node (RNC1) initializes the connection (Co) to afirst core network node (CN1) according to a framing protocol, wherein aset of parameters for the framing of information sent over the interfacebetween the first access node (RNC1) and the first core network node(CN1) is transmitted to the first core network node (CN1), the firstcore network node (CN1) stores the parameter set, the first core networknode (CN1) initializes the connection (Co) to a further core networknode according to said protocol, the further core network node storesthe parameter set, stepwise initialization of the connection (Co) to andstoring of parameters in further core network nodes until a final corenetwork node (CN2) is reached which is connectable to the second accessnode (RNC2), the final core network node (CN2) initializes theconnection (Co) to the second access node (RNC2) according to saidprotocol and the second access node (RNC2) stores the parameter set. 12.Method according to claim 11, wherein a core network node (CN1, CN2) inthe connection (Co) breaks the connection (Co) and initializes aconnection segment (Co′) to a different core network node or access node(RNC3) according to said protocol.
 13. Method according to claim 11 or12, wherein the second access node (RNC2) initializes a reverseconnection (Co) to the final core network node (CN2) according to theprotocol, wherein a second set of parameters for the framing ofinformation is transmitted, and the initialization is performed stepwiseto the first access node (RNC1).
 14. Method according to claim 13,wherein both sets of parameters are incompatible and a core network node(CN1, CN2) inserts a transcoder (TR) into the connection (Co). 15.Method according to claim 13, wherein both sets of parameters areincompatible and a core network node (CN1, CN2) sends a message to acontrol server (MSC1, MSC2) for initiating a modification of connection(Co) parameters by at least one access node (RNC1, RNC2).
 16. Methodaccording to any preceding claim, wherein a core network node (CN1, CN2)acknowledges the initialization to a preceding node (CN1, CN2, RNC1).17. Method according to any preceding claim, wherein the framingprotocol is the Iu protocol.
 18. Method according to any precedingclaim, wherein a core network node (CN1, CN2) in the connection (Co)inserts a function unit into the connection (Co).
 19. Method accordingto any preceding claim, wherein the connection (Co) between two corenetwork nodes (CN1, CN2) is established via a switch.
 20. Methodaccording to any preceding claim, wherein a core network node (CN1, CN2)is adapted to establish connections according to different framingprotocols, checks the framing protocol defined in a request toinitialize a connection (Co) and selects said framing protocol for theinitialization of the connection (Co) to a further node (CN1, CN2, RNC1,RNC2).
 21. Core network node in a communication network, wherein saidnode is interconnected with further core network nodes (CN1, CN2), andcomprises an interface for receiving an initialization request from anaccess node (RNC1) or a further core network node (CN1, CN2) toestablish a connection (Co) according to a framing protocol, aprocessing system to extract a set of parameters for the framingprotocol from the request and initialize the connection (Co) to afurther core network node (CN1, CN2) or an access node (RNC1, RNC2)according to said protocol and a memory (MEM) for storing the extractedparameter set.
 22. Core network node in a communication network, whereinsaid node is interconnected with further core network nodes (CN1, CN2),and comprises an interface for receiving an initialization request froma node (RNC1, CN1, CN2) to establish a connection (Co) according to aframing protocol, a processing system to extract a set of parameters forthe framing protocol from the request and determine an indicator for thepermission of transparent Iu UP transmission after connectionestablishment, and initialize the connection (Co) to a further node(CN1, CN2, RNC1, RNC2) according to said protocol and monitoring thetransmission according to the indicator, and a memory (MEM) for storingthe extracted parameter set and said indicator.
 23. Core network nodeaccording to claim 22, wherein the core network node is adapted toperform a decision to set said indicator.
 24. Core network nodeaccording to any of the claims 21 to 23, wherein the core network nodeis adapted to perform a method according to any of the claims 1 to 20.25. Program unit on a data carrier or loadable into a core network node,said program unit comprising code for performing the steps of receivinga request to initialize a connection (Co) according to a framingprotocol, extracting a set of parameters for the framing of informationaccording to said protocol, storing the parameter set, and initializingthe connection (Co) to a further core network node (CN1, CN2) or anaccess node (RNC1, RNC2) according to said protocol.
 26. Program unitaccording to claim 25, wherein the program unit performs the steps ofdeciding or receiving a decision that an indicator is set, permittingtransparent transmission of Iu user plane after connectionestablishment, and initializing the connection (Co) with a forwarding ofthe indicator.
 27. Program unit according to claim 25 or 26, whereinsaid program unit comprises code for performing any steps of a methodaccording to any of the claims 1 to 20.